Method and apparatus for minimally invasive insertion of intervertebral implants

ABSTRACT

A dilation introducer for orthopedic surgery is provided for minimally invasive access for insertion of an intervertebral implant. The dilation introducer may be used to provide an access position through Kambin&#39;s triangle from a posterolateral approach. A first dilator tube with a first longitudinal axis is provided. A second dilator tube may be introduced over the first, advanced along a second longitudinal axis parallel to but offset from the first. A third dilator tube may be introduced over the second, advanced along a third longitudinal axis parallel to but offset from both the first and the second. An access cannula may be introduced over the third dilator tube. With the first, second, and third dilator tubes removed, surgical instruments may pass through the access cannula to operate on an intervertebral disc and/or insert an intervertebral implant.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 15/835,534,filed Dec. 8, 2017, which is a divisional of U.S. patent applicationSer. No. 15/290,335, filed Oct. 11, 2016, which is a continuation ofU.S. patent application Ser. No. 14/454,418, filed Aug. 7, 2014, whichis a continuation of U.S. patent application Ser. No. 13/934,003, filedJul. 2, 2013, which is a continuation of U.S. patent application Ser.No. 13/416,889, filed Mar. 9, 2012, which claim priority to U.S.Provisional Application No. 61/530,031, filed Sep. 1, 2011, to U.S.Provisional Application No. 61/504,120, filed Jul. 1, 2011, to U.S.Provisional Application No. 61/471,030, filed Apr. 1, 2011, to U.S.Provisional Application No. 61/451,379, filed Mar. 10, 2011, and U.S.patent application Ser. No. 13/416,889, is a continuation-in-part ofU.S. application Ser. No. 13/245,130, filed Sep. 26, 2011. The entiredisclosures of U.S. patent application Ser. No. 15/835,534, filed Dec.8, 2017, U.S. patent application Ser. No. 15/290,335, filed Oct. 11,2016, U.S. patent application Ser. No. 14/454,418, filed Aug. 7, 2014,U.S. patent application Ser. No. 13/934,003, filed Jul. 2, 2013, U.S.patent application Ser. No. 13/416,889, filed Mar. 9, 2012, U.S.Provisional Application No. 61/530,031, filed Sep. 1, 2011, U.S.Provisional Application No. 61/504,120, filed Jul. 1, 2011, U.S.Provisional Application No. 61/471,030, filed Apr. 1, 2011, U.S.Provisional Application No. 61/451,379, filed Mar. 10, 2011, and U.S.application Ser. No. 13/245,130, filed Sep. 26, 2011 are herebyincorporated by reference in their entireties and should be considered apart of this specification.

BACKGROUND OF THE INVENTION Field of the Invention

The present application relates to medical devices and, moreparticularly, to a medical device and method for treating the spine.

Description of the Related Art

The human spine is a flexible weight bearing column formed from aplurality of bones called vertebrae. There are thirty-three vertebrae,which can be grouped into one of five regions (cervical, thoracic,lumbar, sacral, and coccygeal). Moving down the spine, there aregenerally seven cervical vertebrae, twelve thoracic vertebrae, fivelumbar vertebrae, five sacral vertebrae, and four coccygeal vertebrae.The vertebrae of the cervical, thoracic, and lumbar regions of the spineare typically separate throughout the life of an individual. Incontrast, the vertebra of the sacral and coccygeal regions in an adultare fused to form two bones, the five sacral vertebrae which form thesacrum and the four coccygeal vertebrae which form the coccyx.

In general, each vertebra contains an anterior, solid segment or bodyand a posterior segment or arch. The arch is generally formed of twopedicles and two laminae, supporting seven processes—four articular, twotransverse, and one spinous. There are exceptions to these generalcharacteristics of a vertebra. For example, the first cervical vertebra(atlas vertebra) has neither a body nor spinous process. In addition,the second cervical vertebra (axis vertebra) has an odontoid process,which is a strong, prominent process, shaped like a tooth, risingperpendicularly from the upper surface of the body of the axis vertebra.Further details regarding the construction of the spine may be found insuch common references as Gray's Anatomy, Crown Publishers, Inc., 1977,pp. 33-54, which is herein incorporated by reference.

The human vertebrae and associated connective elements are subjected toa variety of diseases and conditions which cause pain and disability.Among these diseases and conditions are spondylosis, spondylolisthesis,vertebral instability, spinal stenosis and degenerated, herniated, ordegenerated and herniated intervertebral discs. Additionally, thevertebrae and associated connective elements are subject to injuries,including fractures and torn ligaments and surgical manipulations,including laminectomies.

The pain and disability related to the diseases and conditions oftenresult from the displacement of all or part of a vertebra from theremainder of the vertebral column. Over the past two decades, a varietyof methods have been developed to restore the displaced vertebra totheir normal position and to fix them within the vertebral column.Spinal fusion is one such method. In spinal fusion, one or more of thevertebra of the spine are united together (“fused”) so that motion nolonger occurs between them. Thus, spinal fusion is the process by whichthe damaged disc is replaced and the spacing between the vertebrae isrestored, thereby eliminating the instability and removing the pressureon neurological elements that cause pain.

Spinal fusion can be accomplished by providing an intervertebral implantbetween adjacent vertebrae to recreate the natural intervertebralspacing between adjacent vertebrae. Once the implant is inserted intothe intervertebral space, osteogenic substances, such as autogenous bonegraft or bone allograft, can be strategically implanted adjacent theimplant to prompt bone ingrowth in the intervertebral space. The boneingrowth promotes long-term fixation of the adjacent vertebrae. Variousposterior fixation devices (e.g., fixation rods, screws etc.) can alsobe utilize to provide additional stabilization during the fusionprocess.

Notwithstanding the variety of efforts in the prior art described above,these intervertebral implants and techniques are associated with anotherdisadvantage. In particular, these techniques typically involve an opensurgical procedure, which results in higher cost, lengthy in-patienthospital stays and the pain associated with open procedures. Inaddition, many intervertebral implants are inserted anteriorly whileposterior fixation devices are inserted posteriorly. This results inadditional movement of the patient. Therefore, there remains a need inthe art for an improved apparatus and method for introducing anintervertebral implant.

SUMMARY OF THE INVENTION

In one embodiment, the implant is advantageously introduced via aminimally invasive procedure, taking a posterolateral approach at leastpartially through Kambin's triangle in a manner that advantageouslyprovides protection to the exiting and traversing nerves. In onearrangement, to facilitate introduction of instruments and/or devices atleast partially through Kambin's triangle a foraminoplasty is formed. Inone embodiment, the foraminoplasty is performed using one or morefeatures provided one or more dilation tubes that can be used to dilatetissue.

In accordance with an embodiment, a dilation introducer for orthopedicsurgery comprises a first dilator tube having a distal portion and aproximal portion, the outer surface of the first dilator tube having afirst outer radius centered around a first longitudinal axis, and afirst longitudinal lumen having a first inner radius; a second dilatortube having a distal portion and a proximal portion, the second dilatortube having a second outer radius centered around a second longitudinalaxis, a second longitudinal lumen having a second inner radius centeredaround the first longitudinal axis, the distal portion of the seconddilator tube having a generally semi-annular cross-section, the secondlumen configured for removably receiving the first dilator tube forslidable movement within the second lumen; wherein the firstlongitudinal axis is parallel to and laterally offset from the secondlongitudinal axis.

In some embodiments, the dilation introducer can be configured forremovably connecting the first and second dilator tubes together in alocked arrangement, whereby in the locked arrangement slidable movementis restricted. In some embodiments, the second dilator tube can berotatable with respect to the first dilator tube around the firstlongitudinal axis. In certain embodiments, the generally semi-annularcross-section of the second dilator tube can be configured such thatwhen the first dilator tube is received within the second dilator tube,the outer radial surface of the first dilator tube is partially exposedat the distal end of the first dilator tube. Further, the opening of thegenerally semi-annular cross-section of the second dilator tube can beoriented opposite the second longitudinal axis with respect to the firstlongitudinal axis. In some embodiments, the second dilator tube cancontain cutting flutes on one side, located opposite the opening of thegenerally semi-annular cross-section of the second dilator tube.

In some embodiments, the dilation introducer can further comprise: athird dilator tube having a distal portion and a proximal portion, thethird dilator tube having a third outer radius centered around a thirdlongitudinal axis, a third longitudinal lumen having a third innerradius centered around the second longitudinal axis, the distal portionof the third dilator tube having a semi-annular cross-section, the thirdlumen configured for removably receiving the second dilator tube forslidable movement within the third lumen; wherein the secondlongitudinal axis is parallel to and laterally offset from the thirdlongitudinal axis. Further, the dilation introducer can comprise: anaccess cannula having a distal portion and a proximal portion, theaccess cannula having a fourth outer radius centered around the thirdlongitudinal axis, a fourth longitudinal lumen having a fourth innerradius centered around the third longitudinal axis, the distal portionof the access cannula having a semi-annular cross-section, the fourthlumen configured for removably receiving the third dilator tube forslidable movement within the fourth lumen. In some embodiments, theaccess cannula can have a smooth outer surface.

In accordance with an embodiment, a method for accessing a patient'sintervertebral disc to be treated in orthopedic surgery is provided,comprising the steps of: passing a first dilator tube along a firstlongitudinal axis through Kambin's triangle until the first dilator tubereaches the intervertebral disc to be treated; passing a second dilatortube along a second longitudinal axis that is parallel to and laterallydisplaced from the first longitudinal axis, until the distal end of thesecond dilator contacts the annulus, wherein the second dilator tube hasa coarse portion oriented towards the inferior pedicle, and wherein thedistal portion of the second dilator tube has a generally semi-annularcross-section, configured such that the second dilator tube does notcontact the exiting nerve during insertion.

In some embodiments, the method can further comprise: passing a thirddilator tube along a third longitudinal axis that is parallel to andlaterally displaced from the second longitudinal axis, until the distalend of the third dilator contacts the annulus, wherein the distalportion of the third dilator tube has cutting flutes oriented towardsthe inferior pedicle, and wherein the distal portion of the thirddilator tube has a generally semi-annular cross-section configured suchthat the third dilator tube does not contact the exiting nerve duringinsertion. Further, the method can comprise forming a further recess inthe inferior pedicle by rotating the second dilator tube back and forth.Alternatively or in addition, the method can further comprise forming afurther recess in the inferior pedicle by longitudinally sliding thesecond dilator tube back and forth. Further still, the method can alsocomprise: passing an access cannula over the third dilator tube untilthe distal end of the third dilator contacts the annulus, wherein thedistal portion of the access cannula has a generally semi-annularcross-section configured such that the access cannula does not contactthe exiting nerve during insertion; rotating the access cannula suchthat generally semi-annular cross-section opens opposite the exitingnerve; and removing the first, second, and third dilator tubes. In someembodiments, the method can further comprise operating on anintervertebral disc by inserting surgical instruments through the accesscannula.

In accordance with an embodiment, a method for performing orthopedicsurgery is provided that can comprise: introducing a first dilator tubethrough Kambin's triangle; introducing a second dilator tube over thefirst dilator tube; and removing bone from the inferior pedicle. In someembodiments, the method can further comprise: introducing a thirddilator tube over the second dilator tube; and removing additional bonefrom the inferior pedicle. In some embodiments, the method can furthercomprise: introducing an access cannula over the third dilator tube; andoperating on the spine through the access cannula.

In accordance with an embodiment, a dilation introducer for orthopedicsurgery is provided that can comprise a first dilator tube having adistal portion and a proximal portion, the outer surface of the firstdilator tube having a first outer radius centered around a firstlongitudinal axis, and a first longitudinal lumen having a first innerradius; and a second dilator tube having a distal portion and a proximalportion, the second dilator tube having a second outer radius centeredaround a second longitudinal axis, a second longitudinal lumen having asecond inner radius centered around the first longitudinal axis, thesecond dilator tube configured to be slidably advanced over the firstdilator tube. In some embodiments, the distal portions first and seconddilator tubes both include cutting surfaces on one outer side of thedilator and a generally smooth surface on an opposite outer side of thedilator tube. In some embodiments, the dilation introducer furtherincludes a neuro-monitoring needle.

Other features and advantages of the present invention will become moreapparent from the following detailed description of the preferredembodiments in conjunction with the accompanying drawings, whichillustrate, by way of example, the operation of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The abovementioned and other features of the inventions disclosed hereinare described below with reference to the drawings of the preferredembodiments. The illustrated embodiments are intended to illustrate, butnot to limit the inventions. The drawings contain the following figures:

FIG. 1 is a lateral elevational view of a portion of a vertebral column.

FIG. 2 is a schematic side view of Kambin's triangle.

FIG. 3 is a perspective view of an access cannula in positioned againsta vertebral column.

FIG. 4A is a plan view of a first and second dilator tubes in a combinedposition.

FIG. 4B is an enlarged detail view of the distal tip of the first andsecond dilator tubes shown in FIG. 4A.

FIG. 5A is a plan view of a third dilator tube.

FIG. 5B is an enlarged detail view of the distal tip of the thirddilator tube shown in FIG. 5A.

FIG. 6A is a side view of the access cannula shown in FIG. 3 .

FIG. 6B is an enlarged detail view of the distal tip of the accesscannula shown in FIG. 6A.

FIG. 7A is a perspective view of a dilation introducer comprising thefirst and second dilator tubes of FIG. 4A, the third dilator tube ofFIG. 5A and the access cannula of FIG. 6A.

FIG. 7B is an enlarged detail view of the distal tip of dilationintroducer shown in FIG. 7A.

FIG. 8A is a perspective view of the dilation introducer of FIG. 7Apositioned against the spine.

FIG. 8B is an enlarged detail view of the second dilator tube of FIG. 7Aintroduced over the first dilator tube of FIG. 7A.

FIG. 9 is a perspective view of the dilation introducer of FIG. 7A, withthe third dilator tube introduced over the second dilator tube.

FIGS. 10A-10D show another embodiment in which a trocar is used in placeof the first dilator tube.

FIG. 11 shows the access point before and after the foraminoplastyperformed by the dilation introducer of FIG. 7A.

FIG. 12A is a perspective view of the dilation introducer of FIG. 7A,with the access cannula introduced over the third dilator tube.

FIG. 12B is a perspective view of the dilation introducer of FIG. 7A,with the access cannula rotated to protect the exiting nerve.

FIG. 12C is a perspective view of the dilation introducer of FIG. 7A,with the first, second, and third dilator tubes removed, while theaccess cannula remains in place.

FIG. 13 is a plan view of an intervertebral implant for delivery throughthe access cannula.

FIG. 14A is a plan view of another embodiment of a first dilator tube.

FIG. 14B is an enlarged detail view of the distal end of the firstdilator tube shown in FIG. 14A.

FIG. 14C is an enlarged detail view of the proximal end of the firstdilator tube shown in FIG. 14A.

FIG. 15A is a plan view of another embodiment of a second dilator tube.

FIG. 15B is an enlarged detail view of the distal end of the seconddilator tube shown in FIG. 15A.

FIG. 15C is an enlarged detail view of the proximal end of the seconddilator tube shown in FIG. 15A.

FIG. 16A is a plan view of another embodiment of a third dilator tube.

FIG. 16B is an enlarged detail view of the distal end of the thirddilator tube shown in FIG. 16A.

FIGS. 16C and 16D are enlarged detail views of the proximal end of thethird dilator tube shown in FIG. 16A.

FIG. 17A is a plan view of another embodiment of an access cannula.

FIG. 17B is an enlarged detail view of the distal end of the accesscannula shown in FIG. 17A.

FIG. 17C is an enlarged detail view of the proximal end of the accesscannula shown in FIG. 17A.

FIG. 18A is a plan view of another embodiment of a dilation introducercomprising the first dilator tube of FIG. 14A, the second dilator tubeof FIG. 15A, the third dilator tube of FIG. 16A, and the access cannulaof FIG. 17A.

FIG. 18B is an enlarged detail view of the distal end of the dilationintroducer shown in FIG. 18A.

FIG. 18C is an enlarged detail view of the proximal end of the dilationintroducer shown in FIG. 18A.

FIG. 19A is a longitudinal cross-sectional view of the dilationintroducer of FIG. 18A.

FIG. 19B is an enlarged detail of the longitudinal cross-sectional viewshown in FIG. 19A.

FIG. 20A is a plan view of a dilation introducer equipped withneuro-monitoring leads and a neuro-monitoring needle.

FIG. 20B is plan view of the neuro-monitoring needle shown in FIG. 20A.

FIG. 20C is an enlarged detail view of a distal tip of aneuro-monitoring needle of FIG. 20A.

FIG. 20D is an enlarged detail view of the neuro-monitoring leads shownin FIG. 20A.

FIG. 21A is a perspective view of another embodiment of anintervertebral implant in an unexpanded state.

FIG. 21B is a perspective view of the intervertebral implant shown inFIG. 20A wherein the implant is in an expanded state.

FIG. 22 is a bottom view of the intervertebral implant shown in FIG.21A.

FIG. 23 is a side view of the intervertebral implant shown in FIG. 21B.

FIG. 24 is a front cross-sectional view of the intervertebral implantshown in FIG. 21B taken along lines 19-19.

FIG. 25A is a bottom perspective view of a lower body portion of theintervertebral implant shown in FIG. 24A.

FIG. 25B is a top perspective view of the lower body portion of theintervertebral implant shown in FIG. 24A.

FIG. 26A is a bottom perspective view of an upper body portion of theintervertebral implant shown in FIG. 24A.

FIG. 26B is a top perspective view of the upper body portion of theintervertebral implant shown in FIG. 24A.

FIG. 27 is a perspective view of an actuator shaft of the intervertebralimplant shown in FIG. 21A.

FIG. 28A is a front perspective view of a proximal wedge member of theintervertebral implant shown in FIG. 21A.

FIG. 28B is a rear perspective view of the proximal wedge member of theintervertebral implant shown in FIG. 21A.

FIG. 29A is a front perspective view of a distal wedge member of theintervertebral implant shown in FIG. 21A.

FIG. 29B is a rear perspective view of the distal wedge member of theintervertebral implant shown in FIG. 21A.

FIG. 30 is a perspective view of a deployment tool according to anembodiment.

FIG. 31 is a side cross-sectional view of the deployment tool shown inFIG. 30 wherein an expandable implant is attached to a distal endthereof.

FIG. 32 is a perspective view of a rasp tool, according to anembodiment.

FIG. 33A is a plan view of a plunger assembly for a graft deliverysystem, according to an embodiment.

FIG. 33B is a longitudinal cross-sectional view of the plunger assemblyshown in FIG. 33A.

FIG. 34A is a plan view of a funnel assembly for a graft deliverysystem, according to an embodiment.

FIG. 34B is a schematic view of the funnel assembly shown in FIG. 34A.

FIG. 34C is an end view of the funnel assembly shown in FIG. 34A.

FIG. 34D is a longitudinal cross-sectional view of the funnel assemblyshown in FIG. 34A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with certain embodiments disclosed herein, an improvedapparatus for inserting an intervertebral implant is provided. Forexample, in one embodiment, the apparatus may be used to insert surgicalinstruments and/or one or more intervertebral implants through aminimally invasive procedure to reduce trauma to the patient and therebyenhance recovery and improve overall results. By minimally invasive,Applicant means a procedure performed percutaneously through an accessdevice in contrast to a typically more invasive open surgical procedure.

Certain embodiments disclosed herein are discussed in the context of anintervertebral implant and spinal fusion because of the device andmethods have applicability and usefulness in such a field. The devicecan be used for fusion, for example, by inserting an intervertebralimplant to properly space adjacent vertebrae in situations where a dischas ruptured or otherwise been damaged. “Adjacent” vertebrae can includethose vertebrae originally separated only by a disc or those that areseparated by intermediate vertebra and discs. Such embodiments cantherefore be used to create proper disc height and spinal curvature asrequired in order to restore normal anatomical locations and distances.However, it is contemplated that the teachings and embodiments disclosedherein can be beneficially implemented in a variety of other operationalsettings, for spinal surgery and otherwise.

As context for the methods and devices described herein, FIG. 1 is alateral view of a vertebral column 10. As shown in FIG. 1 , thevertebral column 10 comprises a series of alternative vertebrae 11 andfibrous intervertebral discs 12 that provide axial support and movementto the upper portions of the body. The vertebral column 10 typicallycomprises thirty-three vertebrae 11, with seven cervical (C1-C7), twelvethoracic (T1-T12), five lumbar (L1-L5), five fused sacral (S1-S5), andfour fused coccygeal vertebrae.

FIG. 2 is a schematic view of Kambin's triangle. This region 20 is thesite of posterolateral access for spinal surgery. It can be defined as aright triangle over the intervertebral disc 12 viewed dorsolaterally.The hypotenuse is the exiting nerve 21, the base is the superior borderof the inferior vertebra 22, and the height is the traversing nerve root23. As will be explained below, in one embodiment, the intervertebraldisc 12 is accessed through this region by performing a foraminoplastyin which a portion of the inferior vertebra is removed such thatsurgical instruments or implants can be introduced at this region of thespine. In such a procedure, it is often desired to protect the exitingnerve and the traversing nerve root. Apparatuses and methods foraccessing the intervertebral disc through Kambin's triangle may involveperforming endoscopic foraminoplasty while protecting the nerve will bediscussed in more detail below. Utilizing foraminoplasty to access theintervertebral disc through Kambin's triangle can have severaladvantages (e.g., less or reduced trauma to the patient) as compared toaccessing the intervertebral disc posteriorly or anteriorly as istypically done in the art. In particular, surgical procedures involvingposterior access often require removal of the facet joint. For example,transforaminal interbody lumbar fusion (TLIF) typically involves removalof one facet joint to create an expanded access path to theintervertebral disc. Removal of the facet joint can be very painful forthe patient, and is associated with increased recovery time. Incontrast, accessing the intervertebral disc through Kambin's trianglemay advantageously avoid the need to remove the facet joint. Asdescribed in more detail below, endoscopic foraminoplasty may providefor expanded access to the intervertebral disc without removal of afacet joint. Sparing the facet joint may reduce patient pain and bloodloss associated with the surgical procedure. In addition, sparing thefacet joint can advantageously permit the use of certain posteriorfixation devices which utilize the facet joint for support (e.g.,trans-facet screws, trans-pedicle screws, and/or pedicle screws). Inthis manner, such posterior fixation devices can be used in combinationwith interbody devices inserted through the Kambin's triangle.

Dilation Introducer

FIGS. 2-7B illustrate an embodiment of a dilation introducer 100 thatcan be used to perform percutaneous orthopedic surgery. As will bedescribed in detail below, the dilation introducer in the illustratedembodiments can comprise an access cannula 30, and a first, second andthird dilator tubes 40, 45, 60. While the illustrated embodimentincludes first, second and third dilator tubes 40, modified embodimentscan include more or less dilator tubes and/or dilator tubes withmodified features. It is also anticipated that in some embodiments, theaccess cannula 30 can be eliminated from the introducer or modified.

FIG. 3 illustrates an embodiment of the access cannula 30, which isshown in a position for performing surgery on an intervertebral disc,for instance transforaminal lumbar interbody fusion. The access cannula30 in the illustrated embodiment has an inner lumen 31 that allows forsurgical instruments and devices to pass through it to access theintervertebral disc 12. The distal tip of the cannula can be orientedsuch that surgical instruments have access to the intervertebral discwithout contacting with the exiting nerve. The position shown in FIG. 3can be achieved by following the method disclosed herein, discussed inmore detail below.

FIGS. 4A and 4B illustrate an embodiment of the first dilator tube 40and second dilator tube 45 of the dilation introducer 100. As shown, inthe illustrated embodiment, the first dilator tube 40 has a distalportion 41, an outer radius 42 and a first longitudinal lumen 43. Theillustrated second dilator tube 45 has a distal portion 46, an outerradius 47 and a second longitudinal lumen 48. As shown, the firstdilator tube can be received within the lumen of the second dilatortube. The outer radius 42 of the first dilator tube can be centeredaround a first longitudinal axis 44. The outer radius 47 of the seconddilator tube can be centered around a second longitudinal axis 49. Inthe illustrated embodiment, the second longitudinal axis 49 is laterallyoffset from the first longitudinal axis 44. In the configuration shown,the outer radius of the first dilator tube is nearly equivalent to theinner radius of the second longitudinal lumen such that the firstdilator tube can be slidably received within the second dilator tub. Thesecond dilator tube 45 can include a handle 50 for rotating the tubeindependently of the first dilator tube 40. In the illustratedembodiment, a collar can be located distal to the handle, with an outerradius larger than the outer radius of the second dilator tube, butsmaller than the outer radius of the handle. In a modified embodiment,the first dilator tube 40 can also a separate handle which can be lockedtogether with the handle 50 of the second dilator tube 45. In oneembodiment, the first and second dilator tubes 40, 45 can lockedlongitudinally locked together, such that slidable movement of the firsttube with respect to the second is restricted. In one embodiment, thedistal portion 46 of the second dilator tube has a flattened edge. Thisflattened edge advantageously prevents the second dilator tube 45 frompenetrating the disc.

FIG. 4B shows an enlarged detail view of the distal portions of thefirst and second dilator tubes 40, 45 of FIG. 4A. The distal portion 46of the second dilator tube 45 can have a generally semi-annularcross-section, configured such that when the first dilator tube 40 isreceived within the second dilator tube 45, the outer radial surface ofthe first dilator tube 40 is partially exposed at the distal portion 46of the second dilator tube 45. The opening of the generally semi-annularcross-section of the second dilator tube can be oriented opposite thesecond longitudinal axis 49 with respect to the first longitudinal axis44. Additionally, the second dilator tube can include cutting flutes orridges 51 on one side, located opposite the opening of the generallysemi-annular cross-section of the second dilator tube 45. In otherembodiments, the cutting flutes may be replaced with a coarse surface(e.g., knurling, sharp edges, abrasive members, etc.) which, whenrotated or slid (e.g., back and forth) against bone, will create arecess therein. As noted above, other mechanisms for removing bone canbe used, and the cutting flutes are shown here by way of example only.As can be seen in FIG. 4B, the inner lumen of the second dilator tube 45can be off-center. In this configuration, the cutting flutes 51 arefurther from the axis of rotation than the side opposite the cuttingflutes. This is particularly advantageous for performing foraminoplastywhile protecting the exiting nerve, as will be discussed in more detailbelow.

Although the illustrated embodiment depicts the first and second dilatortubes as separate elements, in alternative embodiments these two tubescan be coupled formed together as one unified dilator tube with astaggered distal portion. In still other embodiments, the first dilatortube and second dilator tube may be coupled together to form a singlecomponent. The tubes may be joined by, for instance, welding, adhesive,mechanical joints, or any other appropriate means.

In another alternative embodiment, the first dilator tube may beomitted. Instead, a Jamshidi® needle with a removable handle, or asimilar device, may be used to initially define a path to theintervertebral disc. With the handle of the Jamshidi® needle removed,the second dilator tube may be advanced over the Jamshidi® needle, justas with the first dilator tube. In some embodiments, a K-wire or similardevice can be inserted through the Jamshidi® needle and/or dilatortubes.

FIGS. 5A and 5B illustrate and embodiment of the third dilator tube 60,which can be configured to be slidably introduced over the seconddilator tube 45. The third dilator tube 60 can include a distal portion61, a third outer radius 62 centered around a third longitudinal axis63, and a third longitudinal lumen 64 having a third inner radius 65.The third lumen 64 can be configured to removably receive the seconddilator tube (not shown) for slidable movement within the third lumen64. In such a configuration, the third longitudinal axis 63 is parallelto and laterally offset from the second longitudinal axis 49. A handle66 can allow for rotation of the third dilator tube. In one arrangement,a collar can be located distal to the handle 66, with an outer radiuslarger than the outer radius of the third dilator tube 45, but smallerthan the outer radius of the handle.

In some embodiments, a button 67 on the handle 66 allows for theoperator to toggle between a locked and unlocked configuration. In alocked configuration, the second and third dilator tubes are unable toslide relative to one another. In an embodiment, the lockedconfiguration permits the dilator tubes to rotate independently withrespect to one another. In another embodiment, the locked configurationrestrains rotational movement as well as slidable movement. The button67 may comprise a generally rectangular shape with a cut-out largeenough for the collar of the second dilator tube 45 to passtherethrough. A spring located underneath the button 67 provides upwardpressure on the button. When uncompressed, the cut-out portion of thebutton presses firmly against the collar of the second dilator tube 45,which may be received within the handle 66 of the third dilator tube.When uncompressed, the friction of the button 67 against the collarinhibits movement of the third dilator tube 60 with respect to thesecond dilator tube. In some embodiments, the cut-out portion of thebutton may form a notch configured to fit within the ridge on the collarof the third dilator tube. Upon compressing the button 67, the cut-outportion of the button may be moved away from the collar, permitting freemovement of the third dilator tube 60 relative to the second dilatortube 45.

FIG. 5B shows an enlarged detail view of the distal portion of the thirddilator tube of FIG. 5A. The distal portion 61 has a generallysemi-annular cross-section, and cutting flutes 167 for reaming bonelocated opposite the opening of the semi-annular cross-section. As withthe second dilator tube, in other embodiments the cutting flutes may bereplaced or used in combination with a coarse or other cutting orabrading surface which, when rotated or slid against bone, will create arecess therein. As can be seen in FIG. 5B, the inner lumen of the thirddilator tube 60 may be off-center. In this configuration, the cuttingflutes 68 are further from the axis of rotation than the side oppositethe cutting flutes. This is particularly beneficial for performingforaminoplasty while protecting the exiting nerve, as will be discussedin more detail below.

FIGS. 6A and 6B illustrate an embodiment of the access cannula, whichcan be configured to be introduced over the third dilator tube (notshown). The access cannula 30 has a distal portion 32, a fourth outerradius 33 centered around a fourth longitudinal axis 34, and a fourthlongitudinal lumen 31 having a fourth inner radius 35. The accesscannula 30 may be configured to removably receive the third dilator tube(not shown) for slidable movement within the third lumen. A handleallows for rotation of the access cannula 30.

In some embodiments, a button 37 on the handle 36 allows for theoperator to toggle between a locked and unlocked configuration. In alocked configuration, third dilator tube and the access cannula areunable to slide relative to one another. In an embodiment, the lockedconfiguration permits the dilator tubes to rotate independently withrespect to one another. In another embodiment, the locked configurationrestrains rotational movement as well as slidable movement. The button37 may comprise a generally rectangular shape with a cut-out largeenough for the collar of the third dilator tube 60 to pass therethrough.A spring located beneath the button 37 can provide upward pressure onthe button. When uncompressed, the cut-out portion of the button canpress firmly against the collar of the third dilator tube 45, which maybe received within the handle of the access cannula 30. Whenuncompressed, the friction of the button 37 against the collar caninhibit movement of the access cannula 30 with respect to the thirddilator tube 60. Upon compressing the button 37, the cut-out portion ofthe button can be moved away from the collar, permitting free movementof the access cannula 30 relative to the third dilator tube 60.

FIG. 6B shows an enlarged detail view of the distal portion of theaccess cannula of FIG. 6A. The distal portion 32 can have a generallysemi-annular cross-section. In the embodiment shown, the fourthlongitudinal lumen may be centered with respect to the outer radius ofthe access cannula, in contrast to the second and third dilator tubes.In other embodiments, however, the access cannula may also have alongitudinal lumen that may be off-center with respect to the outerradius. In yet another embodiment, the access cannula need not belimited to a cylindrical outer surface. The outer surface could, forinstance, have an elliptical, polygonal, or other cross-sectional shape.

FIGS. 7A and 7B illustrate one embodiment of the dilation introducer 100in an assembled configuration. As shown, the access cannula 30 can bepositioned over the third dilator tube 60, which can be positioned overthe second dilator tube 45, which in turn can be positioned over thefirst dilator tube 40. The handles 50, 151 of the first and seconddilator tubes can be locked together to constrain slidable movement, butallow for the second dilator tube 45 to rotate with respect to the firstdilator tube 40. The third dilator tube 60 can be advanced distallyuntil the distal portion 61 of the third dilator tube aligns with thedistal portion 46 of the second dilator tube. Further, the accesscannula may also be advanced so that the distal portion 32 aligns withthe distal portions 46, 61 of the second and third dilator tubes. Thesecond and third dilator tubes 45, 60 each have cutting flutes 51, 68 ontheir respective distal portions 46, 61. As can be seen, the first,second, and third longitudinal axes 44, 49, 63 are each laterally offsetfrom one another.

In certain embodiments, the first, second and third dilator tubes alongwith the access cannula can be provided with additional stops thatengage the buttons described above. For example, in one embodiment,notches or detents can be provided that engage the button when one tubeis advanced distally and reaches a specific location (e.g., end point).In this manner, forward movement of a tube or cannula can be limitedonce the tube or cannula may be advanced to a desired location.

FIG. 7B shows an enlarged detail view of the dilation introducer of FIG.7A. The distal portions 46, 61, 32 of each of the second and thirddilator tubes 45, 60, and of the access cannula 30 have generallysemi-annular cross-sections. The distal portions 46, 61 of the secondand third dilator tubes in the illustrated embodiment can have flattenededges, to prevent penetration into the intervertebral disc as eachdilator tube is advanced.

Method of Use

FIGS. 8A-13 illustrate one embodiment of a method of performingpercutaneous orthopedic surgery using the dilation introducer. Withinitial reference to FIG. 8A, the first dilator tube 40 can be placedthrough Kambin's triangle 20 until the distal portion 41 abuts or evenpenetrates the intervertebral disc 12. In one arrangement, the seconddilator tube 45 can then be advanced over the first dilator tube 40until the distal portion 46 of the second dilator tube abuts but doesnot enter the intervertebral disc 12.

As discussed above, although the illustrated embodiment shows the firstand second dilator tubes as separate elements, in alternativeembodiments these two tubes may be formed together as one unifieddilator tube with a staggered distal portion. In still otherembodiments, the first dilator tube and second dilator tube may becoupled together to form a single component. In these alternativeembodiments, the unified or coupled dilator tube may be advanced untilthe more distal portion abuts or penetrates the intervertebral disc.

In another alternative embodiment, the first dilator tube may beomitted. Instead, a Jamshidi® needle with a removable handle or similardevice may be used. In such an embodiment, the Jamshidi® needle may befirst introduced to abut or enter the intervertebral disc, after whichthe handle may be removed. Optionally, a K-wire may be inserted into theJamshidi® needle after it is in position either abutting or partiallypenetrating the intervertebral disc. The second dilator tube may then beadvanced over the Jamshidi needle.

FIG. 8B shows an enlarged detail of the second dilator tube 45introduced over the first dilator tube 40. The distal portion 46 of thesecond dilator tube 45 can have a semi-annular cross-section with anopening that forms a recess with respect to the leading edge of the tube45. The second dilator tube 45 can be oriented for advancement over thefirst dilator tube 40 such that the opening of the semi-annularcross-section faces the exiting nerve 21. This technique advantageouslylimits and/or eliminates contact with the exiting nerve. The distalportion 46 of the second dilator tube opposite the opening of thesemi-annular cross-section abuts the inferior vertebrae 22. The cuttingflutes (not shown) are positioned against the inferior vertebrae 22. Thesecond dilator tube 45 may be rotated slightly back and forth, such thatthe cutting flutes create a recess in the inferior vertebrae 22, makingroom for introduction of the third dilator tube. When rotating thesecond dilator tube, care is taken to minimize any trauma inflicted uponthe exiting nerve. Accordingly, in the illustrated embodiment, the tube45 can be used to remove bone on a side of the tube 45 generallyopposite of the nerve 21.

With reference now to FIG. 9 , the third dilator tube 60 can beintroduced over the second dilator tube 45. In one arrangement, thedistal portion 61 of the third dilator tube 60 abuts but does not enterthe intervertebral disc. In the illustrated embodiment, a flattened edgeof the distal portion can help ensure that the third dilator tube 60does not penetrate the intervertebral disc or limit such penetration. Aswith the second dilator tube, the opening of the semi-annularcross-section of the distal portion of the third dilator tube can bepositioned to face the exiting nerve (not shown). Contact between thethird dilator tube 60 and the nerve can thereby be minimized oreliminated. The cutting flutes 68 of the third dilator tube can bepositioned opposite the opening of the semi-annular cross-section, andabut the inferior vertebrae 22. The third dilator tube 60 may be rotatedslightly back and forth, such that the cutting flutes create a furtherrecess in the inferior vertebrae 22, making room for introduction of theaccess cannula. Again, care should be taken during the rotation of thethird dilator tube to ensure that the exiting nerve is not injuredthereby. Accordingly, the third dilator tube can be can be used toremove bone on a side of the tube 60 generally opposite of the nerve 21.

FIGS. 10A-D show an alternative method in which a trocar can be used inplace of the first dilator tube. In some embodiments, the insertionpoint and access trajectory can first be determined. For example, apatient may lie face down on a surgical frame to facilitate a lordoticposition of the lumbar spine. With aid of a lateral x-ray or otherimaging system, a K-wire (or equivalent) can be laid beside the patientand placed to the depth of optimal insertion for the intervertebralimplant. Intersection with the skin can be marked on the K-wire (orequivalent). With the aid of an anteroposterior x-ray or other imagingsystem, the K-wire (or equivalent) can be laid on top of the patient,aligned with the disc in a view that allows for the end plates to beparallel (e.g., Ferguson View or Reverse Ferguson, as applicable). Thedistance between the midline and the previously marked point on theK-wire can define the insertion point.

As illustrated in FIG. 10A, a small skin incision can be made defining atrajectory into the disc can be between 45 and 55 degrees. Next, atrocar 90 can be placed into the center of the disc 12 of the level tobe treated, up to but not through the distal annulus. Alternatively, an11 gauge to 18 gauge access needle can be used. As shown in FIGS. 10B-C,the inner stylet 92 of the trocar (if present) can be removed whilemaintaining the outer sheath 94 in place within the disc 12.Alternatively, a K-wire can be inserted into the disc and the outersheath may be removed. Next, a dilation introducer 96 can be placed overthe outer sheath 94 of the trocar (or over the K-wire, if applicable).The dilation introducer 96 can be aligned so that the smooth edges areoriented towards the exiting nerve root and the foramen. In someembodiments, the dilation introducer 96 can include at least second andthird dilator tubes, each having cutting flutes adapted to performforaminoplasty for improved access to the disc space. In someembodiments, the dilation introducer 96 can function substantially asdescribed elsewhere herein, except that the trocar 90 has replaced thefirst dilator tube. In some embodiments, the second dilator tubes may berotated within +/−45 degrees around the longitudinal axis so that thecutting flutes do not contact the exiting nerve.

FIG. 11 shows the access area before and after the second and thirddilator tubes 45, 60 are rotated to create a recess in the inferiorvertebrae 22. The area 70 in the left image demarcated by a dashed lineis the portion of bone that can be removed by the second and thirddilation tubes 45, 60. This foraminoplasty permits the access cannula tobe introduced without disturbing the exiting nerve 21. The methoddescribed is not limited by the precise location of the recess shown inFIG. 11 . In general, a recess may be formed anywhere along the superiorborder of the inferior vertebrae 22, in order to provide improved accessfor a dilation introducer.

FIG. 12A shows the access cannula 30 introduced over the third dilatortube 60. The distal portion 32 of the access cannula 30 abuts but doesnot enter the intervertebral disc 12. In one embodiment, the distalportion 32 can be equipped with flattened edges to guard againstinsertion into the intervertebral disc. As with the second and thirddilator tubes 45, 60, the opening of the semi-annular cross-section ofthe distal portion 32 of the access cannula 30 can be positionedinitially to face the exiting nerve (not shown). Contact between theaccess cannula 30 and the exiting nerve can thereby be minimized duringinsertion.

As can be seen in FIG. 12B the access cannula 30 can then be rotatedsuch that the opening of the semi-annular cross-section faces oppositethe exiting nerve (not shown). Since, unlike the second and thirddilator tubes 45, 60, the outer surface of the access cannula is smooth,trauma to the exiting nerve may be minimized during this rotation.

Referring now to FIG. 12C, once the access cannula 30 is in position,which in one embodiment comprising until the distal portion 32 abuts theintervertebral disc 12, the cannula 30 can be rotated so that theopening of the semi-annular cross-section faces opposite the exitingnerve (not shown), the first, second, and third dilator tubes 40, 45, 60may be removed. In one embodiment, rotation of the cannula 30 can gentlymove the nerve away from the access site while also protecting the nerveas tools and devices may be inserted through the cannula 30. The accesscannula 30 can then provide an open lumen 31 through which surgicaltools can be introduced to the site of the intervertebral disc 12. Asnoted above, the positioning of the access cannula 30 protects theexiting nerve (not shown) from coming into contact with any of thesurgical tools.

A example of a surgical tool for use through the access cannula isdepicted in FIG. 13 . The intervertebral implant 80 may be introducedthrough the access cannula 30, and released once in position. Although aparticular intervertebral implant is shown here, one of skill in the artwill readily understand that any number of surgical tools may beintroduced through the access cannula. For example, surgical tools to beinserted through the access cannula may include, without limitation,discectomy tools, tissue extractors, bone graft insertion tools, rasps,forceps, drills (e.g,. trephine), rongeurs, curettes, paddledistractors, mechanical distractors, lasers, automated probes, manualprobes, and plasma wands. In one embodiment of use, an opening in thedisc annulus can be formed and a portion of the disc can be removedusing tools advanced through the access cannula 30. The disc space canbe distracted (e.g,. using paddle distractors) before and/or after theimplant 80 and/or different or additional interbody devices are insertedthrough the access cannula 30 and placed between the vertebral bodies tomaintain spacing. In some embodiments the disc nucleus or portionsthereof is removed while leaving the disc annulus. Bone graft and/orother materials such as, for example, bone morphogenetic proteins (BMPs)can be placed between the vertebrae before, while or after positioningthe implant. Fusion can then occur between the vertebrae. In someprocedures, fusion can be augmented with other fixation devices such as,for example, pedicle screws and rod constructions, transfacet andtranspedicle screws, interbody spacers, rods, plates and cages, whichcan be used to stabilize a pair of vertebral bodies together. Forexample, in one arrangement, the fusion is augmented by one or moreposterior fixation devices (e.g transfacet and transpedicle screwsand/or pedicle screws and rods and/or spinous process spacers). In sucha manner, the entire fusion procedure can be done from a posteriorposition and preferably in a minimally invasive (e.g., percutaneousmanner). For example, in one embodiment, the above described procedureis used in combination with the transfacet-pedicular implant system soldby Intervention Spine, Inc. under the trade name PERPOS®, such a systemis also described in U.S. Pat. Nos. 7,998,176 and 7,824,429, theentirety of which are hereby incorporated by reference herein.

FIGS. 14-20D illustrate another aspect of a dilation introducer 1100that can be used to perform percutaneous orthopedic surgery. Thedilation introducer in this embodiment is similar in some respects tothat described above. As will be described in detail below, the proximalportion of the dilation introducer 1100 differs significantly from thatof the dilation introducer 100 described above. The dilation introducer1100 in the illustrated embodiments can comprise an access cannula 130,and a first, second and third dilator tubes 140, 145, 160. While theillustrated embodiment includes first, second and third dilator tubes140, modified embodiments can include more or less dilator tubes and/ordilator tubes with modified features. It is also anticipated that insome embodiments, the access cannula 130 can be eliminated from theintroducer or modified.

FIGS. 14A to 14C illustrate an embodiment of the first dilator tube 140of the dilation introducer 1100. As shown, in the illustratedembodiment, the first dilator tube 140 may have distal portion 141, anouter radius 142 and a first longitudinal lumen 143. The outer radius142 can be centered around first longitudinal axis 144. The distalportion 141 may include a tapered tip 171 of the dilator tube. Theproximal portion 172 of the first dilator tube may include a firstproximal head 173, with a threaded portion 174 distal to the grippingportion 175. In some embodiments, the longitudinal lumen 143 extendsthrough the proximal head 173, such that a guidewire or K-wire may beintroduced through the proximal head 173 and the dilator tube 140.

FIGS. 15A to 15C illustrate an embodiment of the second dilator tube145. In the embodiment shown the second dilator tube has a distalportion 146, and an outer radius 147. The outer radius may be centeredaround a second longitudinal axis 149. The second dilator tube includesa second longitudinal lumen 48 with an inner radius 176. The outerradius 142 of the first dilator tube may be nearly equivalent to theinner radius 176 of the second dilator tube, such that the first dilatortube 140 can be slidably received within the second longitudinal lumen148. The proximal portion 177 of the second dilator tube includes acollar 178.

FIG. 15B shows an enlarged detail view of the distal portion of thesecond dilator tube 145. The distal portion 146 of the second dilatortube may include a flattened edge 179. This flattened edge 179advantageously prevents the second dilator tube 145 from penetrating theintervertebral disc 112. The tip 180 of distal portion 146 can have agenerally semi-annular cross-section, configured such that when thefirst dilator tube 140 is received within the second dilator tube 145,the outer radial surface of the first dilator tube 140 is partiallyexposed at the distal tip 180 of the second dilator tube 145. Theopening of the generally semi-annular cross-section of the seconddilator tube can be oriented opposite the second longitudinal axis 149with respect to the longitudinal axis 127 of the second longitudinallumen.

When the first dilator tube 140 is received within the second dilatortube 145, the longitudinal axis 127 of the second longitudinal lumen isessentially aligned with the first longitudinal axis 144. Additionally,the second dilator tube 145 can include cutting flutes or ridges 151 onone side, located opposite the opening of the generally semi-annularcross-section of the second dilator tube 145. In other embodiments, thecutting flutes 151 may be replaced with a coarse surface (e.g.,knurling, sharp edges, abrasive members, etc.) which, when rotated orslid (e.g., back and forth) against bone, will create a recess therein.As noted above, other mechanisms for removing bone can be used, and thecutting flutes are shown here by way of example only. As can be seen inFIG. 15B, the inner lumen 148 of the second dilator tube 145 can beoff-center. In this configuration, the cutting flutes 151 are furtherfrom the axis of rotation than the side opposite the cutting flutes.This is particularly advantageous for performing foraminoplasty whileprotecting the exiting nerve, as will be discussed in more detail below.

FIG. 15C shows an enlarged detail view of the proximal portion 177 ofthe second dilator tube 145. The collar 178 includes an aperture 181which may be used in conjunction with the third dilator tube, asdescribed in detail below. In alternative embodiments, the aperture 181may be instead replaced with a circumferentially oriented groove.

FIGS. 16A to 16D illustrate and embodiment of the third dilator tube160, which can be configured to be slidably introduced over the seconddilator tube 145. The third dilator tube 160 can include a distalportion 161, a third outer radius 162 centered around a thirdlongitudinal axis 163, and a third longitudinal lumen 164 having a thirdinner radius 165 centered around longitudinal axis 169 that runsparallel to and laterally offset from the third longitudinal axis 163.The third lumen 164 can be configured to removably receive the seconddilator tube 145 for slidable movement within the third lumen 164. Insuch a configuration, the second longitudinal axis 149 essentiallyaligns with the longitudinal axis 169 of the inner lumen 164 of thethird dilator tube 160. The proximal portion 182 includes a handleassembly 183.

FIG. 16B shows an enlarged detail view of the distal portion of thethird dilator tube of FIG. 16A. The distal portion 161 of the thirddilator tube may include a flattened edge 185. This flattened edge 185advantageously prevents the third dilator tube 160 from penetrating theintervertebral disc 112. The tip 184 of the distal portion 161 has agenerally semi-annular cross-section, and cutting flutes 167 for reamingbone located opposite the opening of the semi-annular cross-section. Aswith the second dilator tube, in other embodiments the cutting flutesmay be replaced or used in combination with a coarse or other cutting orabrading surface which, when rotated or slid against bone, will create arecess therein. As can be seen in FIG. 16B, the longitudinal lumen 164of the third dilator tube 160 may be off-center. In this configuration,the cutting flutes 167 are further from the axis of rotation than theside opposite the cutting flutes. This is particularly beneficial forperforming foraminoplasty while protecting the exiting nerve, as will bediscussed in more detail below.

FIGS. 16C and 16D show enlarged detail views of the proximal portion 182of the third dilator tube 160. The proximal portion 182 includes ahandle assembly 183. A first latching button 186 may be configured forconstraining the movement of the third dilator tube relative to thesecond dilator tube, as described in more detail below. In variousembodiments, the latching button 186 may constrain slidable movement,rotational movement, or both. A second latching button 187 may belocated distal the first latching button 186, and may be configured toconstrain the movement of the access cannula relative to the thirddilator tube, as described in more detail below. The distal end of thehandle assembly 183 includes an overhanging lip 191 into which theproximal grip 136 of the access cannula can be removably received. Whenthe proximal grip 136 of the access cannula is received within theoverhanging lip 191, the locking pin 1103 slides within the lockingpinhole 1104 on the proximal grip 136 of the access cannula, therebyrestricting rotational movement of the access cannula relative to thethird dilator tube. In various embodiments, the locking pinhole may beomitted, permitting rotation of the access cannula 130 relative to thethird dilator tube 60.

FIGS. 17A to 17C illustrate an embodiment of the access cannula 130,which can be configured to be introduced over the third dilator tube145. The access cannula 130 has a distal portion 132, a fourthlongitudinal axis 134, and a fourth longitudinal lumen 131 having afourth inner radius 135. The access cannula 130 may be configured toremovably receive the third dilator tube (not shown) for slidablemovement within the third lumen. A handle 136 allows for rotation of theaccess cannula 130.

FIG. 17B shows an enlarged detail view of the distal portion of theaccess cannula of FIG. 17A. The distal portion 132 can have a generallysemi-annular cross-section. In the embodiment shown, the fourthlongitudinal lumen may be centered with respect to the outer radius ofthe access cannula, in contrast to the second and third dilator tubes.In other embodiments, however, the access cannula may also have alongitudinal lumen that is off-center with respect to the outer radius.In yet another embodiment, the access cannula need not be limited to acylindrical outer surface. The outer surface could, for instance, havean elliptical, polygonal, or other cross-sectional shape.

FIG. 17C shows an enlarged detail view of the proximal portion 193 ofthe access cannula of FIG. 17A. The proximal grip 136 may provideadditional leverage while advancing the access cannula over the thirddilator tube. The proximal grip 136 includes a larger diameter portion198 and a smaller diameter portion 199. The smaller diameter portion 199includes a circumferential channel 1107 for use in interlocking with thethird dilator tube, as discussed in detail below. A locking pinhole 1104can receive the locking pin 1103 on the third dilator tube, therebyrestraining rotational movement of the access cannula 160 relative tothe third dilator tube 145.

FIGS. 18A to 18C illustrate one embodiment of the dilation introducer1100 in an assembled configuration. As shown, the access cannula 130 canbe positioned over the third dilator tube 160, which can be positionedover the second dilator tube 145, which in turn can be positioned overthe first dilator tube 140. The handle assembly 183 of the third dilatortube may be in a locked configuration with the proximal grip 136 of theaccess cannula can be locked together to constrain slidable movement,but allow for the access cannula 130 to rotate with respect to the thirddilator tube 160. Additionally, the second dilator tube 145 may belocked together with the third dilator tube to constrain slidablemovement, while still allowing the second dilator tube 145 to rotatewith respect to the third dilator tube. Alternatively, the seconddilator tube may be in a locked configuration preventing both slidableand rotational movement with respect to the third dilator tube 145. Thethird dilator tube 60 can be advanced distally until the distal portion161 of the third dilator tube aligns with the distal portion 46 of thesecond dilator tube. Further, the access cannula 130 may also beadvanced so that the distal portion 32 aligns with the distal portions146, 161 of the second and third dilator tubes. The second and thirddilator tubes 145, 160 each have cutting flutes 151, 167 on theirrespective distal portions 146, 161. As can be seen, the first, second,and third longitudinal axes 144, 149, 163 are each laterally offset fromone another.

In certain embodiments, the first, second and third dilator tubes 140,145, 160 along with the access cannula 130 can be provided withadditional stops that engage the proximal grip 136 of the access cannulaand the handle assembly 183 of the third dilator tube described above.For example, in one embodiment, notches or detents can be provided thatengage the proximal grip 136 or handle assembly 183 when one tube isadvanced distally and reaches a specific location (e.g., end point). Inthis manner, forward movement of a tube or cannula can be limited oncethe tube or cannula is advanced to a desired location

FIG. 18B shows an enlarged detail view of the distal portion of thedilation introducer of FIG. 18A. The distal portions 146, 161, 132 ofeach of the second and third dilator tubes 145, 160, and of the accesscannula 130 may have generally semi-annular cross-sections. The distalportions 146, 161 of the second and third dilator tubes 145, 160 in theillustrated embodiment can have flattened edges 179, 185 to preventpenetration into the intervertebral disc as each dilator tube isadvanced.

FIG. 18C shows an enlarged detail view of the proximal portion of thedilation introducer of FIG. 18A. The proximal grip 136 of the accesscannula 130 is shown in a locked configuration with the handle assembly183 of the third dilator tube 160. The smaller diameter portion (notshown) may be received within the overhanging lip 191 on the distal endof the handle assembly 183. Latching buttons 186, 187 constrain movementof the third dilator tube relative to the second dilator tube, and ofthe access cannula relative to the third dilator tube, respectively. Thegripping portion 175 of proximal head 173 of the first dilator tube 140is visible at the proximal end of the dilation introducer. As shown, thefirst dilator tube may be fastened to the handle assembly 183 by meansof the threaded portion 174 (not shown) on the proximal head 173 and thethreaded receiving portion 190 (not shown) of the handle assembly 183.As shown, this fastening constrains both rotational and slidablemovement of the first dilator tube relative to the third dilator tube.In various embodiments, the first dilator tube may be affixed to thehandle assembly 183 by other means that allow for free rotationalmovement, free slidable movement, or both.

Referring to FIGS. 19A and 19B, a dilation introducer 1100 is shown in alocked assembled configuration. The dilation introducer 1100 includes afirst dilator tube 140, a second dilator tube 145, a third dilator tube160, and an access cannula 130. The first dilator tube has a distalportion 141 with a tapered tip 171, and a proximal portion 172 having aproximal head 173. In various embodiments, the first dilator tube 140may be cannulated, for example to allow passage of a guide wire down thelongitudinal axis 143 of the first dilator tube 140, or the firstdilator tube may be without a lumen and uncannulated. The second dilatortube 145 has a distal tip 180 with a flattened edge 179, a proximalportion 177 with a collar 178, and a longitudinal lumen 148. The firstdilator tube 140 may be removably received within the second dilatortube 145.

The third dilator tube 160 has a distal tip 184 with a flattened edge185, a proximal portion 182 with a handle assembly 183, and alongitudinal lumen 164. The second dilator tube 145 may be removablyreceived in the longitudinal lumen 164 of the third dilator tube 160 forslidable movement within the third dilator tube 160. The threadedportion 174 of the proximal head 173 of the first dilator tube engageswith the interior threaded receiving portion 190 of the handle assembly183 of the third dilator tube 160. With the proximal head of the firstdilator tube affixed to the handle assembly 183, the first and thirddilator tubes 140, 160 may be locked together for length and rotation.The second and third dilator tubes may be connected together in a lockedconfiguration with a first latching button 186 disposed on the handleassembly 183 of the third dilator tube 160 and extending through a firstaperture 1105 in the handle assembly 183 of the third dilator tube 160,so that the first latching button 186 may be moveable between a radiallyinward locking position (arrow 1101) and a radially outward unlockingposition (arrow 1102).

The distal end 196 of the first latching button may be removablyreceived in aperture 181 of the second dilator tube 145 so as to engageand lock the second and third dilators together in the locking position.Alternatively, the latching button may be received in acircumferentially oriented groove of the second dilator tube, which mayor may not extend completely around the second dilator tube. The firstlatching button 186 may be pulled radially outwardly to release thesecond dilator tube 145, to allow the third dilator tube 160 to slidewith respect to the second dilator tube 145.

The access cannula 130 has a distal portion 161, a proximal portion 193,a proximal grip 136, and longitudinal lumen 164. The third dilator tube145 may be removably received within the access cannula 130 for slidablemovement within the longitudinal lumen 131 of the access cannula 130.The third dilator tube 145 and the access cannula 130 also have a lockedconfiguration in which the access cannula 130 may be not permitted toslidably telescope over the third dilator tube 145.

The proximal portion 193 of the access cannula 130 includes a proximalgrip 136 with a larger diameter portion 198 and a smaller diameterportion 199. The smaller diameter portion 199 may be sized to fit underan overhanging lip 191 of the third dilator tube, when the longitudinalaxes of the third dilator tube and access cannula may be aligned. Theremay be a circumferentially oriented channel 1107 in the exterior of thesmaller diameter portion 919 for receiving a distal end 197 of a secondlatching button 187. The circumferentially oriented channel 1107 doesnot need to extend completely around the exterior of the smallerdiameter portion 199.

The third dilator tube 145 and the access cannula 130 may be connectedtogether in a locked configuration with the second latching button 187disposed on the overhanging lip 191 of the handle assembly 183 of thethird dilator tube 145. The second latching button extends through anaperture 1106 in the overhanging lip 191 of the handle assembly 183 andmay be movable between a radially inward locking position (arrow 194)and a radially outward unlocking position (arrow 195). The distal end197 of the second latching button 187 may be removably received in thechannel 107 located in the smaller diameter portion 199 of the accesscannula 130, in the locking position, to lock the third dilator tube 45and the access cannula 130 in the locked assembled configuration. Thesecond latching button 187 may be pulled radially outward to release theaccess cannula 130 to slide to the unlocked configuration. Furthermore,the second and third dilator tubes 140, 145 may be removed together as aunit from the access cannula 130. In other words, the first dilator tube140 and second dilator tube 145 can be kept locked together and can beremoved from the access cannula 130 by unlocking the second latchingbutton 187 alone. An advantage of this embodiment is that the latchingbuttons 186, 187 may be both removable from the surgical field with therelease of the third dilator tube from the access cannula 130.

The access cannula being free of protuberances, such as the latchingbuttons, is less likely to catch surgical sponges and sutures, forexample, on the dilation introducer.

Dilation Introducer with Neuro-Monitoring

FIGS. 20A to 20D show another aspect of a dilation introducer, in whichthe first dilator tube may be replaced with a neuro-monitoring needle1108. The neuro-monitoring needle 1108 includes a wire 1109 which may beenclosed by a needle cannula 1110, with the wire 1109 exposed at thedistal tip 1111. The needle cannula 1110 may be surrounded by dielectriccoating 1112 along its length for insulation. For example, the wire 1109can comprise stainless steel and the dielectric coating 1112 cancomprise parylene. As noted above, a knob 1115 may be located on theproximal portion 1116 of the neuro-monitoring needle 1108. A firstneuro-monitoring lead 1113 may be attached to the proximal portion 177of the second dilator tube 145. A second neuro-monitoring lead 1114 maybe attached to the proximal portion 183 of the third dilator tube 160.

The neuro-monitoring needle 1108 can be made from several components.The wire 1108 portion can be stainless steel coated with dielectriccoating 1112 of parylene. The distal tip 1111 of the wire 1109 can beexposed so that it can transmit current. The needle cannula 1110 whichcovers the wire 1109 can also comprise stainless steel coated withparylene. In some embodiments, this needle cannula could also bedescribed as an exchange tube where once the wire is removed a K-wirecould be placed down it and into the disc space. The wire 1109 can beattached to a handle at the proximal end ultimately protrude from thehandle, serving as the electrode to attach a neuromonitoring system. Insome embodiments, the proximal diameter can be parylene coated, whilethe rest of the wire 1109 can be uncoated to transmit the current.

The wire 1109 may comprise a conductive material, such as silver,copper, gold, aluminum, platinum, stainless steel, etc. A constantcurrent may be applied to the wire 1109. The needle cannula 1110 may beinsulated by dielectric coating 1112. Although the coating shown here isdielectric, any sufficiently insulative coating may be used.Alternatively, an insulative sleeve may encase the wire. Thisarrangement protects the conductive wire 1109 at all points except themost distal tip 1111. As the exposed tip of the wire 1109 is advancedthrough the tissue, it continues to be supplied with current. When thetip 1111 approaches a nerve, the nerve may be stimulated. The degree ofstimulation to the nerve is related to the distance between the distaltip 1111 and the nerve. Stimulation of the nerve may be measured by,e.g., visually observing the patient's leg for movement, or by measuringmuscle activity through electromyography (EMG) or various other knowntechniques.

Utilizing this configuration may provide the operator with addedguidance as to the positioning of the first dilator tube to the surgicalaccess point and through Kambin's triangle. With each movement, theoperator may be alerted when the tip of the first dilator tubeapproaches or comes into contact with a nerve. The operator may use thistechnique alone or in conjunction with other positioning assistancetechniques such as fluoroscopy and tactile feedback. The amount ofcurrent applied to the wire 1109 may be varied depending on thepreferred sensitivity. Naturally, the greater the current supplied, thegreater nerve stimulation will result at a given distance from thenerve. In various embodiments the current applied to the conductive wire1109 may not be constant, but rather periodic or irregular.Alternatively, pulses of current may be provided only on demand from theoperator.

Although not shown here, a similar configuration may be applied to thesecond and third dilator tubes, and to the access cannula. Each mayinclude a conductive wire embedded within the tube, or it may beseparately attached. In either configuration, a distal tip of conductivewire may be exposed and the wire may be provided with current. As thedilator tube or access cannula is advanced through the tissue andtowards the access site, nerve stimulation may be monitored as describedabove. The current supplied to each of the first, second, and thirddilator tubes and to the access cannula may be controlled independently,so that when nerve stimulation is observed, the operator may supplycurrent separately to each wire to determine which wire or wires arenearest to the nerve. Alternatively, current may be supplied only to onewire at any given point in the procedure. For example, the current maybe supplied to the wire associated with the dilator tube or accesscannula that is being moved at that point in the operation.

In some embodiments, the second and third dilator tubes can comprisealuminum that has been anodized and then coated with parylene. Certainareas of the second and third dilator tubes can be masked from theanodization and parylene coating so that they can transmit the current.For example, the distal tips of the second and third dilator tubes canbe exposed so as to conduct current therethrough. The exposed portionscan be passivated to resist rusting, pitting, or corrosion. The exposedportions can be made by using a stainless steel pin pressed into thesecond and third dilator tubes. The pin can aid in locating the secondand third dilator tubes on x-ray or fluoroscopy, and additionally canfaciliatate the transmission of current through the second and thirddilator tubes to the area of contact. Electrode attachments for thesecond and third dilator tubes can be coated with parylene on theproximal larger diameter to prevent current from flowing into the user.The rest of the electrode can be uncoated, but passivated to resistrusting, pitting, or corrosion. The electrodes can attach such that thecurrent is transmitted to the internal area of the second and thirddilator tubes so that it can be transmitted distally through the exposedareas on the tips of the tubes. These tubes are attached to Radelhandles, which being a polymer are also insulators. The third dilatortube can be made from stainless steel, coated with nylon or otherpolymer, such as Teflon, followed by a parylene coating. In embodimentsin which the dilator tube comprises stainless steel, no additional x-raymarker is required.

Although the method as described above utilizes an embodiment of thedilation introducer as shown in FIGS. 3-7B, it will be understood thatthe procedure may be adapted for use with various other embodiments ofthe dilation introducer. For instance, the dilation introducer withalternative handle assembly, as shown in FIGS. 14A-19C, may be used withappropriate modifications to the method described above. For instance,as the proximal head 173 of the first dilator tube 140 may be screwedinto the handle assembly 183 of the third dilator tube 160, the firstdilator tube 140 must be unscrewed and removed prior to advancing thethird dilator tube over the second dilator tube. Additionally, thelatching buttons 186, 187 of the handle assembly 183 may be used tocontrol the locking and unlocking of the dilator tubes relative to oneanother.

Alternatively, the dilation introducer equipped with neuro-monitoring,as shown in FIGS. 20A-D, may be substituted. The method performed may bethen similar to that described above, except that in addition the methodinvolves monitoring nerve stimulation to assist with placement andguidance of the dilator tubes and access cannula. As described above,the current supplied to the conductive wires may be varied andcontrolled in order to determine the optimal location for the dilationintroducer and/or access cannula.

Implant

With respect to the implant 80 described above, the implant 80 cancomprise any of a variety of types of interbody devices configured to beplaced between vertebral bodies. The implant 80 can be formed from ametal (e.g., titanium) or a non-metal material such as plastics, PEEK™,polymers, and rubbers. Further, the implant components can be made ofcombinations of non metal materials (e.g., PEEK™, polymers) and metals.The implant 80 can be configured with a fixed or substantially fixedheight, length and width as shown, for example, in the embodiment ofFIG. 13 . In other embodiments, the implant can be configured to beexpandable along one or more directions. For example, in certainembodiments the height of the implant can be expanded once the deviceadvanced through the access cannula and positioned between vertebralbodies (e.g., within the disc space within the annulus).

Additional detail of one embodiment of such an expandable implant can befound in FIGS. 21A-31 . As shown, in FIGS. 21A-B, in the illustratedembodiments, the implant 200 can be configured such that proximal anddistal wedge members 206, 208 are interlinked with upper and lower bodyportions 202, 204. The upper and lower body portions 202, 204 caninclude slots (slot 220 is shown in FIG. 21A, and slots 220, 222 areshown in FIG. 21B; the configuration of such an embodiment of the upperand lower body portions 202, 204 is also shown in FIGS. 21A-22B,discussed below). In such an embodiment, the proximal and distal wedgemembers 206, 208 can include at least one guide member (an upper guidemember 230 of the proximal wedge member 206 is shown in FIG. 21A and anupper guide member 232 of the distal wedge member 208 is shown in FIG.23 ) that at least partially extends into a respective slot of the upperand lower body portions. The arrangement of the slots and the guidemembers can enhance the structural stability and alignment of theimplant 200.

In addition, it is contemplated that some embodiments of the implant 200can be configured such that the upper and lower body portions 202, 204each include side portions (shown as upper side portion 240 of the upperbody portion 202 and lower side portion 242 of the lower body portion204) that project therefrom and facilitate the alignment,interconnection, and stability of the components of the implant 200.FIG. 21B is a perspective view of the implant 200 wherein the implant200 is in the expanded state. The upper and lower side portions 240, 242can be configured to have complementary structures that enable the upperand lower body portions 202, 204 to move in a vertical direction.Further, the complementary structures can ensure that the proximal endsof the upper and lower body portions 202, 204 generally maintain spacingequal to that of the distal ends of the upper and lower body portions202, 204. The complementary structures are discussed further below withregard to FIGS. 22-26B.

Furthermore, as described further below, the complementary structurescan also include motion limiting portions that prevent expansion of theimplant beyond a certain height. This feature can also tend to ensurethat the implant is stable and does not disassemble during use.

In some embodiments, the actuator shaft 210 can facilitate expansion ofthe implant 200 through rotation, longitudinal contract of the pin, orother mechanisms. The actuator shaft 210 can include threads thatthreadably engage at least one of the proximal and distal wedge members206, 208. The actuator shaft 210 can also facilitate expansion throughlongitudinal contraction of the actuator shaft as proximal and distalcollars disposed on inner and outer sleeves move closer to each other toin turn move the proximal and distal wedge members closer together. Itis contemplated that in other embodiments, at least a portion of theactuator shaft can be axially fixed relative to one of the proximal anddistal wedge members 206, 208 with the actuator shaft being operative tomove the other one of the proximal and distal wedge members 206, 208 viarotational movement or longitudinal contraction of the pin.

Further, in embodiments wherein the actuator shaft 210 is threaded, itis contemplated that the actuator shaft 210 can be configured to bringthe proximal and distal wedge members closer together at differentrates. In such embodiments, the implant 200 could be expanded to aV-configuration or wedged shape. For example, the actuator shaft 210 cancomprise a variable pitch thread that causes longitudinal advancement ofthe distal and proximal wedge members at different rates. Theadvancement of one of the wedge members at a faster rate than the othercould cause one end of the implant to expand more rapidly and thereforehave a different height that the other end. Such a configuration can beadvantageous depending on the intervertebral geometry and circumstantialneeds.

In other embodiments, the implant 200 can be configured to includeanti-torque structures 250. The anti-torque structures 250 can interactwith at least a portion of a deployment tool during deployment of theimplant to ensure that the implant maintains its desired orientation(see FIGS. 30-31 and related discussion). For example, when the implant200 is being deployed and a rotational force is exerted on the actuatorshaft 210, the anti-torque structures 250 can be engaged by anon-rotating structure of the deployment tool to maintain the rotationalorientation of the implant 200 while the actuator shaft 210 is rotated.The anti-torque structures 250 can comprise one or more inwardlyextending holes or indentations on the proximal wedge member 206, whichare shown as a pair of holes in FIGS. 21A-B. However, the anti-torquestructures 250 can also comprise one or more outwardly extendingstructures.

According to yet other embodiments, the implant 200 can be configured toinclude one or more apertures 252 to facilitate osseointegration of theimplant 200 within the intervertebral space. As mentioned above, theimplant 200 may contain one or more bioactive substances, such asantibiotics, chemotherapeutic substances, angiogenic growth factors,substances for accelerating the healing of the wound, growth hormones,antithrombogenic agents, bone growth accelerators or agents, and thelike. Indeed, various biologics can be used with the implant 200 and canbe inserted into the disc space or inserted along with the implant 200.The apertures 252 can facilitate circulation and bone growth throughoutthe intervertebral space and through the implant 200. In suchimplementations, the apertures 252 can thereby allow bone growth throughthe implant 200 and integration of the implant 200 with the surroundingmaterials.

FIG. 22 is a bottom view of the implant 200 shown in FIG. 21A. As showntherein, the implant 200 can comprise one or more protrusions 260 on abottom surface 262 of the lower body portion 204. Although not shown inthis Figure, the upper body portion 204 can also define a top surfacehaving one or more protrusions thereon. The protrusions 260 can allowthe implant 200 to engage the adjacent vertebrae when the implant 200 isexpanded to ensure that the implant 200 maintains a desired position inthe intervertebral space.

The protrusions 260 can be configured in various patterns. As shown, theprotrusions 260 can be formed from grooves extending widthwise along thebottom surface 262 of the implant 200 (also shown extending from a topsurface 264 of the upper body portion 202 of the implant 200). Theprotrusions 260 can become increasingly narrow and pointed toward theirapex. However, it is contemplated that the protrusions 260 can be one ormore raised points, cross-wise ridges, or the like.

FIG. 22 also illustrates a bottom view of the profile of an embodimentof the upper side portion 240 and the profile of the lower side portion242. As mentioned above, the upper and lower side portions 240, 242 caneach include complementary structures to facilitate the alignment,interconnection, and stability of the components of the implant 200.FIG. 22 also shows that in some embodiments, having a pair of each ofupper and lower side portions 240, 242 can ensure that the upper andlower body portions 202, 204 do not translate relative to each other,thus further ensuring the stability of the implant 200.

As illustrated in FIG. 22 , the upper side portion 240 can comprise agroove 266 and the lower side portion can comprise a rib 268 configuredto generally mate with the groove 266. The groove 266 and rib 268 canensure that the axial position of the upper body portion 202 ismaintained generally constant relative to the lower body portion 204.Further, in this embodiment, the grooves 266 and rib 268 can also ensurethat the proximal ends of the upper and lower body portions 202, 204generally maintain spacing equal to that of the distal ends of the upperand lower body portions 202, 204. This configuration is alsoillustratively shown in FIG. 23 .

Referring again to FIG. 22 , the implant 200 is illustrated in theunexpanded state with each of the respective slots 222 of the lower bodyportion 204 and lower guide members 270, 272 of the respective ones ofthe proximal and distal wedge members 206, 208. In some embodiments, asshown in FIGS. 21A-22 and 24-26B, the slots and guide members can beconfigured to incorporate a generally dovetail shape. Thus, once a givenguide member is slid into engagement with a slot, the guide member canonly slide longitudinally within the slot and not vertically from theslot. This arrangement can ensure that the proximal and distal wedgemembers 206, 208 are securely engaged with the upper and lower bodyportions 202, 204.

Furthermore, in FIG. 23 , a side view of the embodiment of the implant200 in the expanded state illustrates the angular relationship of theproximal and distal wedge members 206, 208 and the upper and lower bodyportions 202, 204. As mentioned above, the dovetail shape of the slotsand guide members ensures that for each given slot and guide member, agiven wedge member is generally interlocked with the give slot to onlyprovide one degree of freedom of movement of the guide member, and thusthe wedge member, in the longitudinal direction of the given slot.

Accordingly, in such an embodiment, the wedge members 206, 208 may notbe separable from the implant when the implant 200 is in the unexpandedstate (as shown in FIG. 21A) due to the geometric constraints of theangular orientation of the slots and guide members with the actuatorshaft inhibiting longitudinal relative movement of the wedge members206, 208 relative to the upper and lower body portions 202, 204. Such aconfiguration ensures that the implant 200 is stable and structurallysound when in the unexpanded state or during expansion thereof, thusfacilitating insertion and deployment of the implant 200.

Such an embodiment of the implant 200 can therefore be assembled byplacing or engaging the wedge members 206, 208 with the actuator shaft210, moving the wedge members 206, 208 axially together, and insertingthe upper guide members 230, 232 into the slots 220 of the upper bodyportion 202 and the lower guide members 270, 272 into the slots 222 ofthe lower body portion 204. The wedge members 206, 208 can then be movedapart, which movement can cause the guide members and slots to engageand bring the upper and lower body portions toward each other. Theimplant 200 can then be prepared for insertion and deployment byreducing the implant 200 to the unexpanded state.

During assembly of the implant 200, the upper and lower body portions202, 204 can be configured to snap together to limit expansion of theimplant 200. For example, the upper and lower side portions 240, 242 cancomprise upper and lower motion-limiting structures 280, 282, as shownin the cross-sectional view of FIG. 24 . After the wedge members 206,208 are engaged with the upper and lower body portions 202, 204 andaxially separated to bring the upper and lower body portions 202, 204together, the upper motion-limiting structure 280 can engage the lowermotion-limiting structure 282. This engagement can occur due todeflection of at least one of the upper and lower side portions 240,242. However, the motion-limiting structures 280, 282 preferablycomprise interlocking lips or shoulders to engage one another when theimplant 200 has reached maximum expansion. Accordingly, after the wedgemembers 206, 208 are assembled with the upper and lower body portions202, 204, these components can be securely interconnected to therebyform a stable implant 200.

Referring again to FIG. 23 , the implant 200 can define generally convextop and bottom surfaces 264, 262. In modified embodiments, the shape canbe modified.

FIGS. 25A-B illustrate perspective views of the lower body portion 204of the implant 200, according to an embodiment. These Figures provideadditional clarity as to the configuration of the slots 222, the lowerside portions 242, and the lower motion-limiting members 282 of thelower body portion 204. Similarly, FIGS. 26A-B illustrate perspectiveviews of the upper body portion 202 of the implant 200, according to anembodiment. These Figures provide additional clarity as to theconfiguration of the slots 220, the upper side portions 240, and theupper motion-limiting members 280 of the upper body portion 202.Additionally, the upper and lower body portions 202, 204 can also definea central receptacle 290 wherein the actuator shaft can be received.Further, as mentioned above, the upper and lower body portions 202, 204can define one or more apertures 252 to facilitate osseointegration.

FIG. 27 is a perspective view of an actuator shaft 210 of the implant200 shown in FIG. 21 . In this embodiment, the actuator shaft 210 can bea single, continuous component having threads 294 disposed thereon forengaging the proximal and distal wedge members 206, 208. The threads canbe configured to be left hand threads at a distal end of the actuatorshaft 210 and right hand threads at a proximal other end of the actuatorshaft for engaging the respective ones of the distal and proximal wedgemembers 208, 206. Accordingly, upon rotation of the actuator shaft 210,the wedge members 206, 208 can be caused to move toward or away fromeach other to facilitate expansion or contraction of the implant 200.Further, as noted above, although this embodiment is described andillustrated as having the actuator shaft 210 with threads 294.

In accordance with an embodiment, the actuator shaft 210 can alsocomprise a tool engagement section 296 and a proximal engagement section298. The tool engagement section 296 can be configured as a to beengaged by a tool, as described further below. The tool engagementsection 296 can be shaped as a polygon, such as a hex shape. As shown,the tool engagement section 296 is star shaped and includes six points,which configuration tends to facilitate the transfer of torque to theactuator shaft 210 from the tool. Other shapes and configurations canalso be used.

Furthermore, the proximal engagement section 298 of the actuator shaft210 can comprise a threaded aperture. The threaded aperture can be usedto engage a portion of the tool for temporarily connecting the tool tothe implant 200. It is also contemplated that the proximal engagementsection 298 can also engage with the tool via a snap or press fit.

FIG. 28A-B illustrate perspective views of the proximal wedge member 206of the implant 200. As described above, the proximal wedge member caninclude one or more anti-torque structures 250. Further, the guidemembers 230, 270 are also illustrated. The proximal wedge member 206 cancomprise a central aperture 300 wherethrough an actuator shaft can bereceived. When actuator shaft 210 is used in an embodiment, the centralaperture 300 can be threaded to correspond to the threads 294 of theactuator shaft 210. In other embodiments, the actuator shaft can engageother portions of the wedge member 206 for causing expansion orcontraction thereof.

FIG. 29A-B illustrate perspective views of the distal wedge member 208of the implant 200. As similarly discussed above with respect to theproximal wedge member 206, the guide members 232, 272 and a centralaperture 302 of the proximal wedge member 206 are illustrated. Thecentral aperture 302 can be configured to receive an actuator shafttherethrough. When actuator shaft 210 is used in an embodiment, thecentral aperture 302 can be threaded to correspond to the threads 294 ofthe actuator shaft 210. In other embodiments, the actuator shaft canengage other portions of the wedge member 208 for causing expansion orcontraction thereof.

Referring now to FIG. 30 , there is illustrated a perspective view of adeployment tool 400 according to another embodiment. The tool 400 cancomprise a handle section 402 and a distal engagement section 404. Thehandle portion 402 can be configured to be held by a user and cancomprise various features to facilitate implantation and deployment ofthe implant.

According to an embodiment, the handle section 402 can comprise a fixedportion 410, and one or more rotatable portions, such as the rotatabledeployment portion 412 and the rotatable tethering portion 414. In suchan embodiment, the tethering portion 414 can be used to attach theimplant to the tool 400 prior to insertion and deployment. Thedeployment portion 412 can be used to actuate the implant and rotate theactuator shaft thereof for expanding the implant. Then, after theimplant is expanded and properly placed, the tethering portion 414 canagain be used to untether or decouple the implant from the tool 400.

Further, the distal engagement section 404 can comprise a fixed portion420, an anti-torque component 422, a tethering rod (element 424 shown inFIG. 31 ), and a shaft actuator rod (element 426 shown in FIG. 27 ) tofacilitate engagement with and actuation of the implant 200. Theanti-torque component 422 can be coupled to the fixed portion 420. Asdescribed above with reference to FIGS. 21A-B, in an embodiment, theimplant 200 can comprise one or more anti-torque structures 250. Theanti-torque component 422 can comprise one or more protrusions thatengage the anti-torque structures 250 to prevent movement of the implant200 when a rotational force is applied to the actuator shaft 210 via thetool 400. As illustrated, the anti-torque component 422 can comprise apair of pins that extend from a distal end of the tool 400. However, itis contemplated that the implant 200 and tool 400 can be variouslyconfigured such that the anti-torque structures 250 and the anti-torquecomponent 422 interconnect to prevent a torque being transferred to theimplant 200. The generation of the rotational force will be explained ingreater detail below with reference to FIG. 31 , which is a side-crosssectional view of the tool 400 illustrating the interrelationship of thecomponents of the handle section 402 and the distal engagement section404.

For example, as illustrated in FIG. 31 , the fixed portion 410 of thehandle section 402 can be interconnected with the fixed portion 420 ofthe distal engagement section 404. The distal engagement section 404 canbe configured with the deployment portion 412 being coupled with theshaft actuator rod 426 and the tethering portion 414 being coupled withthe tethering rod 424. Although these portions can be coupled to eachother respectively, they can move independently of each other andindependently of the fixed portions. Thus, while holding the fixedportion 410 of the handle section 402, the deployment portion 412 andthe tethering portion 414 can be moved to selectively expand or contractthe implant or to attach the implant to the tool, respectively. In theillustrated embodiment, these portions 412, 414 can be rotated to causerotation of an actuator shaft 210 of an implant 200 engaged with thetool 400.

As shown in FIG. 31 , the tether rod 424 can comprise a distalengagement member 430 being configured to engage a proximal end of theactuator shaft 210 of the implant 200 for rotating the actuator shaft210 to thereby expand the implant from an unexpanded state to andexpanded state. The tether rod 424 can be configured with the distalengagement member 430 being a threaded distal section of the rod 424that can be threadably coupled to an interior threaded portion of theactuator shaft 210.

In some embodiments, the tool 400 can be prepared for a single-use andcan be packaged with an implant preloaded onto the tool 400. Thisarrangement can facilitate the use of the implant and also provide asterile implant and tool for an operation. Thus, the tool 400 can bedisposable after use in deploying the implant.

Referring again to FIG. 30 , an embodiment of the tool 400 can alsocomprise an expansion indicator gauge 440 and a reset button 450. Theexpansion indicator gauge 440 can be configured to provide a visualindication corresponding to the expansion of the implant 200. Forexample, the gauge 440 can illustrate an exact height of the implant 200as it is expanded or the amount of expansion. As shown in FIG. 31 , thetool 400 can comprise a centrally disposed slider element 452 that canbe in threaded engagement with a thread component 454 coupled to thedeployment portion 412.

In an embodiment, the slider element 452 and an internal cavity 456 ofthe tool can be configured such that the slider element 452 is providedonly translational movement in the longitudinal direction of the tool400. Accordingly, as the deployment portion 412 is rotated, the threadcomponent 454 is also rotated. In such an embodiment, as the threadcomponent 454 rotates and is in engagement with the slider component452, the slider element 452 can be incrementally moved from an initialposition within the cavity 456 in response to the rotation of thedeployment portion 412. An indicator 458 can thus be longitudinallymoved and viewed to allow the gauge 440 to visually indicate theexpansion and/or height of the implant 200. In such an embodiment, thegauge 440 can comprises a transparent window through which the indicator458 on the slider element 452 can be seen. In the illustratedembodiment, the indicator 458 can be a marking on an exterior surface ofthe slider element 452.

In embodiments where the tool 400 can be reused, the reset button 450can be utilized to zero out the gauge 440 to a pre-expansion setting. Insuch an embodiment, the slider element 452 can be spring-loaded, asshown with the spring 460 in FIG. 31 . The reset button 450 candisengage the slider element 452 and the thread component 454 to allowthe slider element 452 to be forced back to the initial position.

Additional details and embodiments of an expandable implant can be foundin U.S. patent application Ser. No. 2008/0140207, filed Dec. 7, 2007 asU.S. patent application Ser. No. 11/952,900, the entirety of which ishereby incorporated by reference herein.

Bone Rasp

Another example of a surgical tool for use through the access cannula isa bone rasp. One embodiment of such an bone rasp can be found in FIG. 32. As shown in this figure, a rasp tool 800 can be configured to beinserted through the access cannula 30 into the intervertebral discspace. The rasping tool 800 can then be used to abrade or file theinferior surface of the superior vertebrae and/or the superior surfaceof the inferior vertebrae. The rasping tool 800 may comprise anelongated body 810 and a scraping component 812. A handle 816 may beproximally attached to the elongated body 810. As shown, the raspingtool 800 includes an open sleeve 808 within which the elongate body 810is slidably received. This configuration may permit the elongated body810 and scraping component 812 to slide relative to the open sleeve 808.

The entire assembly, including the elongate body 810, open sleeve 808,and scraping component 812 are dimensioned such that the rasping tool800 can slide longitudinally within the access cannula 30. in use, therasp tool 800 may be inserted through the access cannula until itreaches the intervertebral disc space. Using the handle 716, a physicianmay slide the elongate body 810 and scraping component 812 backward andforward, while the open sleeve 808 remains stationary relative to theaccess cannula 30. In other embodiments, the open sleeve 808 is omitted,and the elongate body 810 is inserted directly into the access cannula30, and is dimensioned to slidably move within it. In certainembodiments, the elongate body 808 may freely rotate within the opensleeve 808, or within the access cannula 30, in order to permit thephysician to rasp a surface at any desired angle. In other embodiments,the orientation of the elongate body 808 may be fixed, such that raspingis only permitted along a predetermined angle relative to the accesscannula.

In certain embodiments, the rasping tool may be expandable. For example,a rasp tool 800 can be configured to define an unexpanded configuration.When the tool 800 is initially inserted into the working sleeve, thetool 800 can be positioned in the unexpanded configuration. After thetool 800 is advanced into the intervertebral disc, the tool 800 can beexpanded to the expanded configuration.

The tool 800 can comprise an elongated body 810 and one or more scrapingcomponents 812. The scraping components 812 can each comprise an outersurface that is configured to scrape or create friction against thedisc. For example, the outer surfaces can be generally arcuate andprovide an abrasive force when in contact with the interior portion ofthe disc. In particular, it is contemplated that once the tool 800 isexpanded, the scraping components 812 can rasp or scrape against thevertebral end plates of the disc from within an interior cavity formedin the disc. In this manner, the tool 800 can prepare the surfaces ofthe interior of the disc by removing any additional gelatinous nucleusmaterial, as well as smoothing out the general contours of the interiorsurfaces of the disc. The rasping may thereby prepare the vertebralendplates for fit with the implant as well as to promote bony fusionbetween the vertebrae and the implant. Due to the preparation of theinterior surfaces of the disc, the placement and deployment of theimplant will tend to be more effective.

It is contemplated that the tool 800 can comprise an expansion mechanismthat allows the scraping components 812 to move from the unexpanded tothe expanded configuration. For example, the tool 800 can be configuredsuch that the scraping components 812 expand from an outer dimension orheight of approximately 9 mm to approximately 13 mm. In this regard, theexpansion mechanism can be configured similarly to the expansionmechanisms of the implants disclosed herein, the disclosure for which isincorporated here and will not be repeated.

Further, it is contemplated that the scraping components 812 cancomprise one or more surface structures, such as spikes, blades,apertures, etc. that allow the scraping components 812 to not onlyprovide an abrasive force, but that also allowed the scraping components812 to remove material from the disc. In this regard, as in any of theimplementations of the method, a cleaning tool can be used to removeloosened, scraped, or dislodged disc material. Accordingly, in variousembodiments of the methods disclosed herein, and embodiment of the tool800 can be used to prepare the implant site (the interior cavity of thedisc) to optimize the engagement of the implant with the surfaces of theinterior of the disc (the vertebral end plates).

After the implant site has been prepared, the implant can be advancedthrough the second working sleeve into the disc cavity. Once positioned,the implant can be expanded to its expanded configuration. For example,the implant can be expanded from approximately 9 mm to approximately12.5 mm. The surgeon can adjust the height and position of the implantas required. Additionally, other materials or implants can then beinstalled prior to the removal of the second working sleeve and closureof the implant site.

Graft Delivery Device

With reference now to FIGS. 33A to 34D, a bone graft delivery device isdisclosed which may be inserted through the access cannula for use inthe intervertebral space. For example, the bone graft material can beinserted into the intervertebral disc space in order to promote rapidfixation between the adjacent vertebrae. The bone graft material may beinserted before insertion of an intervertebral implant. Alternatively,the bone graft material may be inserted following insertion of theintervertebral implant. In some implementations, bone graft material isdelivered both prior to and following insertion of the intervertebralimplant. Bone graft material may be autologous, allograft, xenograft, orsynthetic. In addition to bone graft material, other materials may beintroduced to the treatment site, as desired. For example, bonemorphogenetic proteins may be introduced with a carrier medium, such asa collagen, through use of the disclosed delivery device.

FIGS. 33A and 33B show a plunger assembly 900. The plunger assembly 900includes an elongate shaft 902. In some embodiments, the shaft 902 issubstantially rigid. The plunger assembly 900 includes a distal tip 906,which is connected to the elongate shaft 902 by a flexible member 904. Aplunger knob 908 is positioned at the proximal end of the plungerassembly 900.

FIGS. 34A-D show a funnel assembly 910. The funnel assembly 910 includesa bent shaft 912. The bent shaft 912 may be substantially straight alongthe majority of its length, with a bend positioned nearer the distalportion of the bent shaft 912. In other embodiments, a plurality ofbends may be included in the bent shaft 912. The particular orientationof the bend may be adjusted to provide for improved access to theintervertebral disc space when the funnel assembly is inserted throughthe access cannula. A receptacle 914 is located at the proximal end ofthe funnel assembly 910.

The bent shaft 912 includes a central lumen 916 which runs from theopening of the receptacle at the proximal end to the distal opening ofthe funnel assembly 910. The plunger assembly 900 is configured to beslidably received within the funnel assembly 910. Accordingly, thedimensions of the distal tip 906, flexible member 904 and the elongateshaft 902 are such that they may slide into the opening at thereceptacle 914 of the funnel assembly 910. As the plunger assembly 900is advanced through the lumen 916 of the funnel assembly 910, the distaltip 906 may reach the bent portion of the bent shaft 912. Due to thepliable nature of flexible member 904, the distal tip 906 may beadvanced along lumen 916 through the curve in bent shaft 912. Theplunger knob 908 may be configured to be mated with the receptacle 914,such that when the plunger assembly 900 is fully advanced into thefunnel assembly 910, the plunger knob 908 contacts the receptacle 914.As shown, the receptacle 914 has a hollow conical shape, with theplunger knob 908 having a corresponding conical surface. The shapes ofboth the receptacle 914 and plunger knob 908 may be varied, and need notbe limited to conical shapes, nor even to corresponding shapes. Slot 918is an opening on the outer surface of bent shaft 912, and may bepositioned near the distal end of the funnel assembly 910. The slot 918may provide for an additional aperture through which bone graft materialmay flow during injection to the treatment site, as described in moredetail below.

In use, bone graft material is introduced into the lumen 916 of thefunnel assembly 910. The bone graft material may either be introducedthrough the receptacle 914 at the proximal end, or it may be back-filledby inserting the bone graft material through the opening in the distalend of the funnel assembly 910. Upon insertion of the plunger assembly900 into the funnel assembly 910, the distal tip 906 pushes the bonegraft material along the length of the bent shaft 912 and eventually outof the funnel assembly 910.

It should also be noted that bone chips and/or autograft must be madeinto pieces small enough to flow through the funnel assembly 910.Otherwise, the funnel assembly 910 may become congested and the bonegraft may not flow into the target site as desired.

Once the bone graft material is loaded into the funnel assembly, thebone graft material can be deployed at the target site. The funnelassembly can be inserted into the access cannula until the distal tip ofthe funnel assembly is positioned adjacent to the target site. Thelocation of the distal tip of the funnel instrument can be modified toany desired location for deploying the graft material at the targetsite. Due to the bend in the funnel assembly 910, the device may berotated within the access cannula in order to achieve different anglesof approach. The bend may therefore provide for improved access todifferent regions of the intervertebral disc space. Then, inserting theplunger assembly 900 through the funnel assembly 910, a desired amountof graft material can be injected at the target site. In certainembodiments, the funnel assembly 910 and plunger assembly 900 can eachbe placed over a k-wire. The plunger assembly 900 can then be advancedinto the funnel assembly 910 to deploy the graft into the disc.

As the bone graft material flows through the lumen 916 of funnelassembly 910, it passes slot 918 near the distal end of the bent tube912. In some embodiments, the opening of slot 918 is smaller than theopening of lumen 916, such that, absent backpressure, bone graftmaterial preferentially exits the funnel assembly 910 through the distalopening of lumen 916. As the target site is filled with bone graftmaterial, however, it may become increasingly difficult to advance theplunger assembly 900 and introduce new bone graft material through thelumen 916. In the event that such resistance is present, some of thebone graft material may be forced through slot 918, thereby providing analternate distribution route for the bone graft material. In certainembodiments, a plurality of slots 918 may be provided around thecircumference of bent shaft 912. The position of slot 918 may be varieddepending on the desired distribution of bone graft material at thetreatment site. As discussed above, the funnel assembly 910 may berotated within the access cannula, allowing for bone graft materialexiting the slot 918 to be deposited in various locations at thetreatment site.

Once the implant and, if applicable, bone graft material have beeninserted into the intervertebral disc space, supplemental internalspinal fixation can be employed to facilitate fusion. For example,spinal fixation can include facet screw fixation systems, facetcompression devices, and/or posterior pedicle screw and rod systems.

Although the embodiments shown herein depict a dilation introducer withthree dilator tubes and one access cannula, other variations arepossible. For instance, as noted above, a dilation introducer mayinclude only two dilator tubes and an access cannula. In anotherembodiment, a dilation introducer may include four or more dilator tubesand an access cannula. In a modified arrangement, the access cannulawould be replaced by a dilator tube, wherein the dilator tube withcutting flutes would remain in place, with the inner dilator tubesremoved to provide access for surgical tools. The skilled artisan willreadily ascertain that many variations of this sort are possible withoutdeparting from the scope of the present invention.

The specific dimensions of any of the embodiment disclosed herein can bereadily varied depending upon the intended application, as will beapparent to those of skill in the art in view of the disclosure herein.Moreover, although the present inventions have been described in termsof certain preferred embodiments, other embodiments of the inventionsincluding variations in the number of parts, dimensions, configurationand materials will be apparent to those of skill in the art in view ofthe disclosure herein. In addition, all features discussed in connectionwith any one embodiment herein can be readily adapted for use in otherembodiments herein to form various combinations and sub-combinations.The use of different terms or reference numerals for similar features indifferent embodiments does not imply differences other than those whichmay be expressly set forth. Accordingly, the present inventions areintended to be described solely by reference to the appended claims, andnot limited to the preferred embodiments disclosed herein.

What is claimed is:
 1. A method of performing an endoscopic procedure inan intervertebral disc space through a Kambin's triangle of a human, themethod comprising the steps of: inserting a guide member through tissueof the human toward the intervertebral disc space along a generallytransforaminal approach along a trajectory; applying an electricalcurrent to the guide member during the inserting step; and during theapplying step, determining that the guide member is approaching a nerveas the guide member is inserted through the tissue of the human duringthe inserting step; changing the trajectory to a changed trajectory, anddriving the tube through tissue of the human toward the intervertebraldisc space along the changed trajectory along the generallytransforaminal approach toward the Kambin's triangle; introducing atleast one dilator tube over the guide member; introducing an accesscannula over the at least one dilator tube; removing the guide memberand the at least one dilator tube; and performing the endoscopicprocedure in the intervertebral disc space through the access cannulaand through the Kambin's triangle.
 2. The method claim 1, wherein thedetermining step comprises determining that a nerve of the Kambin'striangle has been stimulated by the electrical current when theelectrically conductive instrument approaches the nerve.
 3. The methodof claim 2, wherein the determining step comprises the step of visuallyobserving a visual indication that the guide member is approaching thenerve.
 4. The method of claim 3, wherein the changing step removes thevisual indication.
 5. The method of claim 4, wherein the visualindication comprises a movement of a leg of the human.
 6. The method ofclaim 1, wherein the driving step comprises driving the tube along achanged trajectory that extends through the Kambin's triangle.
 7. Themethod of claim 6, wherein the step of performing the foraminoplastycomprises rotating a bone cutting instrument so as to remove bone. 8.The method of claim 1, comprising the step of performing aforaminoplasty under endoscopic visualization prior to the step ofperforming the endoscopic procedure.
 9. The method of claim 8, whereinthe step of rotating the bone cutting instrument comprises rotating thebone cutting instrument about an axis that extends along the changedtrajectory.
 10. The method of claim 9, wherein the endoscopic procedurecomprises removing disc material from the intervertebral disc space. 11.The method of claim 1, wherein the at least one dilator tube comprises aplurality of dilator tubes, and the step of introducing the accesscannula comprises introducing the access cannula over a largest one ofthe plurality of dilator tubes.
 12. The method of claim 1, wherein theendoscopic procedure comprises inserting an intervertebral implantthrough the access cannula and into the intervertebral disc space, andsubsequently expanding the intervertebral implant from a first height toa second height greater than the first height.
 13. The method of claim1, wherein the applying step comprises applying a constant current tothe guide member.
 14. The method of claim 1, wherein the applying stepcomprises varying an amount of the current to the guide member.
 15. Themethod of claim 1, further comprising the step of attaching a pediclescrew to a pedicle of a vertebra.